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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Altitude deviation altitude overshot - air carrier crew relied on the B737-300's FMC/VNAV to level off from a steep descent (started down late because of center) and it failed to do so.
| Attributes | |
| ACN | 299503 |
| Time | |
| Date | 199503 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : pie airport : tpa |
| State Reference | FL |
| Altitude | msl bound lower : 10700 msl bound upper : 11000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zma tracon : tpa |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | descent other |
| Route In Use | arrival other arrival star : star enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Dash 8 Series Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 195 flight time total : 15000 |
| ASRS Report | 299503 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 180 flight time total : 15080 |
| ASRS Report | 299208 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : overshoot conflict : airborne less severe non adherence : clearance non adherence : required legal separation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course flight crew : overcame equipment problem |
| Consequence | Other |
| Miss Distance | horizontal : 0 vertical : 800 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We were descending to 11000 ft at bridge intersection. Because of earlier traffic conflicts clearance was late and we had a high rate of descent. The aircraft was on autoplt, LNAV and VNAV. We had been pointed out traffic, the DH-8, earlier at 10000 ft our 3 O'clock. We got a TCASII alert and an 'RA' 'decrease vertical speed' as we were approaching 11000 ft we at first monitored our performance and when we realized we were going to bust 11000 ft both captain (PNF) and first officer (PF) applied back pressure to level off. We leveled off maybe 10800 ft and returned to 11000 ft during this time the DH-8 had moved to our 10 O'clock position passing under us. During subsequent level off, speed reduction, retrimming, first officer allowed aircraft to descend back to 10700 ft before reengaging autoplt and leveling again at 11000 ft. During the time we were reacting to the 'RA' ATC asked if we still had the dash 8 and were level at 11000 ft. ATC was then vectoring both of us to the same runway 36L, but had issued no speed control so for several mi we were directly over the DH-8 and rapidly approaching the point of descent. ATC finally split us and sent the DH-8 to runway 36R. I have 5000 hours in B-737 - 300/400 and I do not understand why this time we overshot our altitude with LNAV and VNAV and the correct altitude selected.
Original NASA ASRS Text
Title: ALTDEV ALT OVERSHOT - ACR CREW RELIED ON THE B737-300'S FMC/VNAV TO LEVEL OFF FROM A STEEP DSCNT (STARTED DOWN LATE BECAUSE OF CTR) AND IT FAILED TO DO SO.
Narrative: WE WERE DSNDING TO 11000 FT AT BRIDGE INTXN. BECAUSE OF EARLIER TFC CONFLICTS CLRNC WAS LATE AND WE HAD A HIGH RATE OF DSCNT. THE ACFT WAS ON AUTOPLT, LNAV AND VNAV. WE HAD BEEN POINTED OUT TFC, THE DH-8, EARLIER AT 10000 FT OUR 3 O'CLOCK. WE GOT A TCASII ALERT AND AN 'RA' 'DECREASE VERT SPD' AS WE WERE APCHING 11000 FT WE AT FIRST MONITORED OUR PERFORMANCE AND WHEN WE REALIZED WE WERE GOING TO BUST 11000 FT BOTH CAPT (PNF) AND FO (PF) APPLIED BACK PRESSURE TO LEVEL OFF. WE LEVELED OFF MAYBE 10800 FT AND RETURNED TO 11000 FT DURING THIS TIME THE DH-8 HAD MOVED TO OUR 10 O'CLOCK POS PASSING UNDER US. DURING SUBSEQUENT LEVEL OFF, SPD REDUCTION, RETRIMMING, FO ALLOWED ACFT TO DSND BACK TO 10700 FT BEFORE REENGAGING AUTOPLT AND LEVELING AGAIN AT 11000 FT. DURING THE TIME WE WERE REACTING TO THE 'RA' ATC ASKED IF WE STILL HAD THE DASH 8 AND WERE LEVEL AT 11000 FT. ATC WAS THEN VECTORING BOTH OF US TO THE SAME RWY 36L, BUT HAD ISSUED NO SPD CTL SO FOR SEVERAL MI WE WERE DIRECTLY OVER THE DH-8 AND RAPIDLY APCHING THE POINT OF DSCNT. ATC FINALLY SPLIT US AND SENT THE DH-8 TO RWY 36R. I HAVE 5000 HRS IN B-737 - 300/400 AND I DO NOT UNDERSTAND WHY THIS TIME WE OVERSHOT OUR ALT WITH LNAV AND VNAV AND THE CORRECT ALT SELECTED.
Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.